CN110262130B

CN110262130B - Backlight module

Info

Publication number: CN110262130B
Application number: CN201910555755.0A
Authority: CN
Inventors: 杜佳臻; 沈文斌; 陈士杰; 黄绍宗; 徐理智
Original assignee: AU Optronics Corp
Current assignee: AU Optronics Corp
Priority date: 2018-11-26
Filing date: 2019-06-25
Publication date: 2021-12-21
Anticipated expiration: 2039-06-25
Also published as: CN110262130A

Abstract

The invention discloses a backlight module, which comprises a light source, a metal back plate, a light guide plate and a quantum dot film. The metal back plate package has a bearing surface. The light guide plate is located on the bearing surface of the metal back plate and comprises a light incident surface and a plurality of non-light incident surfaces, wherein the light source corresponds to the light incident surface, and a gap is formed between the light incident surface and the light source. The quantum dot film is arranged on the light guide plate and comprises a body, an extending part and a plurality of bending parts. The body is positioned on the light guide plate. The extending part extends from the body to the light source direction, and the extending part and the light source part are overlapped on a first projection plane parallel to the body. The bending parts respectively extend towards the direction of the non-light incident surface. The bending part and the non-light incident surface are respectively overlapped on a second projection plane vertical to the first projection plane. The bending part is not contacted with the bearing surface of the metal back plate. The invention can be beneficial to the color gamut and the color balance of the display.

Description

Backlight module

Technical Field

The invention relates to the field of displays, in particular to a backlight module.

Background

In the backlight module of the existing liquid crystal display, the quantum dots can be excited by blue light through the arrangement of the quantum dot film, and then the quantum dots emit red light, green light and the like, so that the wider color gamut standard can be achieved.

However, moisture and oxygen easily diffuse into the quantum dot film from the sidewall of the quantum dot film, which may cause the quantum dot to fail. Quantum dot failure typically occurs first at the edge of the quantum dot film, which may result in incident blue light not being able to react effectively with the quantum dots and passing directly through, so blue blooming is seen at the edge of the active area of the display. With the narrow frame and even frameless design of the display, the problem of blue light appearing at the edge of the active area of the display will be more and more influenced by the color gamut of the whole display.

Disclosure of Invention

The invention aims to provide a backlight module which is beneficial to the balance of color gamut and color of a display.

To achieve the above object, a backlight module is provided. The backlight module comprises a light source, a metal back plate, a light guide plate and a quantum dot film. The metal back plate package has a bearing surface. The light guide plate is located on the bearing surface of the metal back plate and comprises a light incident surface and a plurality of non-light incident surfaces, wherein the light source corresponds to the light incident surface, and a gap is formed between the light incident surface and the light source. The quantum dot film is arranged on the light guide plate and comprises a body, an extending part and a plurality of bending parts. The body is positioned on the light guide plate. The extending part extends from the body to the light source direction, the extending part and the light source part are overlapped on a first projection plane parallel to the body, the bending parts respectively extend to the direction of the non-light-incident surface, and the bending parts and the non-light-incident surface are respectively overlapped on a second projection plane vertical to the first projection plane; wherein, the bending part is not contacted with the bearing surface of the metal back plate.

In some embodiments, the length of the extension is represented by the following equation (one):

wherein A is the length of the extension, A₁Is the length of the gap, A₂Length of light source, Ly width of light guide plate, delta_LGPIs the thermal expansion coefficient, delta, of the light guide plate_QDThe thermal expansion coefficient of the quantum dot film and Δ T are temperature change values.

In some embodiments, the bending portions respectively shield the non-light incident surface.

Further, in some embodiments, the bending portion includes a first bending portion and a second bending portion, the first bending portion is located on the opposite side of the extending portion, the two bending portions are respectively connected to the first bending portion and the extending portion, the length of the first bending portion is represented by the following equation (two), and the length of the second bending portion is represented by the following equation (three):

equation (ii): a is₁≥Lz，

Equation (c):

wherein a is₁Is the length of the first bending part, a₂The length of the second bending part, Lx the length of the light guide plate, Lz the thickness of the light guide plate, delta_LGPIs the thermal expansion coefficient, delta, of the light guide plate_QDThe thermal expansion coefficient of the quantum dot film and Δ T are temperature change values.

Further, in some embodiments, each of the second bending portions includes a folding line extending along a direction parallel to the width direction of the light guide plate. In some embodiments, each of the second bending portions includes a plurality of folding lines extending along a direction parallel to the width direction of the light guide plate.

In some embodiments, the bending portions are respectively adhered to the non-light incident surface of the light guide plate.

In some embodiments, the backlight module further comprises a reflective sheet and an optical sheet, the light guide plate is located on the reflective sheet, and the optical sheet is located on the quantum dot film.

Further, in some embodiments, the backlight module further comprises a backlight frame. The backlight frame comprises a side wall and an extension wall. The metal back plate is further provided with a side wall, and the side wall extends from one end of the bearing surface along the direction parallel to the thickness of the light guide plate. The side wall is connected with the side wall of the metal back plate. The light source is arranged on the side wall of the metal back plate, the side wall of the backlight frame extends along the direction parallel to the thickness of the light guide plate, the extending wall is connected with the side wall and extends towards the direction vertical to the thickness of the light guide plate, and the light source, the reflecting sheet, the light guide plate, the quantum dot film and a part of the optical sheet are positioned between the metal back plate and the extending wall.

Furthermore, in some embodiments, the metal back plate includes a slot, and the backlight frame side wall includes a hook, and the hook is engaged with the slot, so that the metal back plate and the side wall have a common plane.

In summary, the backlight module ensures that the projection of the extension portion and the light source in the vertical direction is overlapped when the quantum dot film expands with heat and contracts with cold through the extension portion of the quantum dot film, and meanwhile, the extension portion is bent to the non-light-incident surface by the bending portion of the quantum dot film and is not connected with the metal back plate at the bottom. Therefore, the blue light leakage of the light source is avoided, the phenomenon that the edge of the active area of the display is blue light is prevented, and the color gamut and the color balance of the display are ensured.

The invention is described in detail below with reference to the drawings and specific examples, but the invention is not limited thereto.

Drawings

Fig. 1 is a schematic cross-sectional view of a backlight module in a first embodiment in a first direction.

Fig. 2 is a schematic cross-sectional view of the backlight module of the first embodiment in a second direction.

Fig. 3 is a partial top view of the backlight module of the first embodiment before bending.

Fig. 4 is a partial top view of the backlight module of the second embodiment before bending.

Fig. 5 is a schematic cross-sectional view of the backlight module of the second embodiment in a second direction.

Fig. 6 is a partial top view of the backlight module of the third embodiment before bending.

Fig. 7 is a schematic cross-sectional view of a backlight module of a third embodiment in a second direction.

FIG. 8 is a top view of an embodiment of a backlight module in a second direction.

FIG. 9 is a bottom view of an embodiment of a backlight module in a second direction.

Wherein, the reference numbers:

1 backlight module 10 light source

20 light guide plate 21 light incident surface

23 non-light-incident surface 25 non-light-incident surface

30 quantum dot film 31 body

33 bent portion of extended portion 35 (first bent portion)

37 bending part (second bending part) 371 folding line

40 metal back plate 41 bearing surface

43 side wall 45 side surface

451 spline 51 reflector plate

53 optical sheet 60 backlight frame

61 side wall 611 hook

63 extending wall 70 adhesive layer

Length of A extension₁Length of the gap

A₂Length a of the light source₁Length of the first bending part

a₂Length of the second bending part Lx length of the light guide plate

Width Lz light guide plate thickness of Ly light guide plate

G-gap P1 first plane of projection

P2 second plane of projection

Detailed Description

In the drawings, the widths of some of the elements, regions, etc. are exaggerated for clarity. Like reference numerals refer to like elements throughout the specification. It will be understood that when an element such as it is referred to as being "on" or "connected to" another element, it can be directly on or connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or "directly connected to" another element, there are no intervening elements present.

It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, or sections, these elements, components, regions, and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, or section from another element, component, region, layer, or section. Thus, a "first element," "component," "region," or "portion" discussed below could be termed a second element, component, region, or portion without departing from the teachings herein.

Furthermore, relative terms, such as "lower" or "bottom" and "upper" or "top," may be used herein to describe one element's relationship to another element, as illustrated. It will be understood that relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures. For example, if the device in one of the figures is turned over, elements described as being on the "lower" side of other elements would then be oriented on "upper" sides of the other elements. Thus, the exemplary term "lower" can include both an orientation of "lower" and "upper," depending on the particular orientation of the figure. Similarly, if the device in one of the figures is turned over, elements described as "below" other elements would then be oriented "above" the other elements. Thus, the exemplary terms "below" or "beneath" can encompass both an orientation of above and below.

Fig. 1 is a schematic cross-sectional view of a backlight module in a first embodiment in a first direction. Fig. 2 is a schematic cross-sectional view of the backlight module of the first embodiment in a second direction. Fig. 3 is a partial top view of the backlight module of the first embodiment before bending. Here, the first direction is substantially a-a direction in fig. 3, and the first direction is substantially B-B direction in fig. 3.

As shown in fig. 1 to 3, the backlight module 1 includes a light source 10, a light guide plate 20, a quantum dot film 30, and a metal back plate 40. The metal back plate 40 includes a supporting surface 41 and sidewalls 43. The light source 10 is disposed on the sidewall 43. The sidewall 43 extends perpendicularly from one side of the bearing surface 41. The light guide plate 20 is disposed on the supporting surface 41. The light guide plate 20 includes a light incident surface 21 and a plurality of non-light incident surfaces 23 and 25. The light source 10 corresponds to the light incident surface 21, and a gap G is formed between the light incident surface 21 and the light source 10. The quantum dot film 30 is disposed on the light guide plate 20, and the quantum dot film 30 includes a body 31, an extending portion 33, and a plurality of bending

portions

35 and 37. The main body 31 is positioned on the light guide plate 20, and a projection in a vertical direction thereof substantially overlaps the light guide plate 20. The extension 33 extends from the body 31 toward the light source 10.

As shown in fig. 1, the extension 33 partially overlaps the light source 10 on the first projection plane P1 of the parallel body 31. As shown in fig. 2, the bent portions 37 extend toward the non-incident surface 23, and the bent portions 37 overlap the non-incident surface 25 on a second projection plane P2 perpendicular to the first projection plane P1. Although not shown in the drawings, it is understood that the bending portion 35 and the corresponding non-light incident surface 23 are also arranged in the same manner as described above. In addition, the

bent portions

35 and 37 do not contact the bearing surface 41 of the metal back plate 40.

Here, the length of the extension 33 is expressed by the following equation (one),

equation (I):

wherein A is the length of the extension 33, A₁Is the length of the gap G, A₂Length of the light source 10, Ly width of the light guide plate 20, δ_LGPThe thermal expansion coefficient, delta, of the light guide plate 20_QDThe thermal expansion coefficient of the quantum dot film 30 and Δ T are temperature change values.

Here, the light source 10 may be a blue light emitting diode to excite the quantum dots in the quantum dot film 30 to generate red light and green light, so as to achieve the color standard of a wide color gamut. In addition, the operating temperature of the backlight module 1 is generally 25 ℃ to 40 ℃, and Δ T can be preset to be 15 ℃ to set the length of the maximum extension portion 33, so that it can be ensured that the projection of the extension portion 33 and the light source 10 in the vertical direction is overlapped during thermal expansion, and the edge leakage of blue light can be avoided, so as to ensure the color gamut and color balance of the display.

As shown in fig. 1 and fig. 2, in some embodiments, the backlight module 1 further includes a reflective sheet 51 and an optical sheet 53. The light guide plate 20 is positioned on the reflective sheet 51, and the optical sheet 53 is positioned on the quantum dot film 30. The reflective sheet 51 is generally white to reflect ambient light or other light reflected or refracted inward into the light guide plate 20, and the optical sheets 53 can guide light emitted from the light guide plate 20.

As shown in fig. 1 and fig. 2, in some embodiments, the backlight module 1 further includes a backlight frame 60. The backlight frame 60 includes sidewalls 61 and extension walls 63. The side wall 61 is assembled with the side wall 43 of the metal back plate 40, and the side wall 43 of the metal back plate 40 and the side wall 61 of the backlight frame 60 extend along a direction parallel to the thickness of the light guide plate 20. The extension wall 63 connects the sidewalls 61 and extends toward a direction perpendicular to the thickness of the light guide plate 20. The light source 10, a portion of the light guide plate 20, a portion of the quantum dot film 30, a portion of the reflective sheet 51, and a portion of the optical sheet 53 are located between the supporting surface 41 of the metal back plate 40 and the extending wall 63 of the backlight frame 60.

Thus, the light emitted from the light source 10 can be prevented from directly passing through the side edge by the extending wall 63, thereby reducing the chance of light leakage and ensuring the color gamut and color balance of the display. Further, the backlight frame 60 may be black, so as to absorb the light penetrating through the light guide plate 20, thereby reducing the chance of light leakage.

As shown in fig. 3, the bending

portions

35 and 37 can be divided into a first bending portion 35 and a second bending portion 37. The first bending portion 35 is located at the opposite side of the extending portion 33, and the second bending portion 37 is connected to the first bending portion 35 and the extending portion 33 respectively. As shown in fig. 1 and 2, the second bent portion 37 shields the non-light-incident surface 25, respectively, but it is understood that the first bent portion 35 also shields the non-light-incident surface 23 in the other direction although not shown in the drawings. Furthermore, the first bending portion 35 and the second bending portion 37 can also be adhered to the non-light incident surfaces 23 and 25 of the light guide plate 20 through the adhesive layer 70, respectively, and the first bending portion 35 and the second bending portion 37 are not in contact with the metal back plate 40. Thus, it is ensured that the light emitted from the side of the light guide plate 20 can excite the quantum dots in the quantum dot film 30 first, and in addition, the side of the quantum dot film 30 is bent to reduce the permeation of moisture and air, even if the quantum dots in the quantum dot film 30 have a failure problem, the edge position is bent to be located in the invalid area, and the color gamut in the active area of the display area is not directly affected.

As shown in fig. 1 to 3, in order to avoid the blue light from passing through the non-light incident surfaces 23 and 25, the problem of expansion with heat and contraction with cold is considered as the light incident surface 21. The length of the first bent portion 35 is expressed by the following equation (two), and the length of the second bent portion 37 is expressed by the following equation (three).

Equation (ii): a is₁≥Lz，

Equation (c):

wherein a is₁Is the length, a, of the first bent portion 35₂The length of the second bent portion 37, Lx the length of the light guide plate 20, Lz the thickness of the light guide plate 20, and δ_LGPThe thermal expansion coefficient, delta, of the light guide plate 20_QDThe thermal expansion coefficient of the quantum dot film 30 and Δ T are temperature change values. Thus, the non-light incident surfaces 23 and 25 can be completely shielded by the first bent portion 35 and the second bent portion 37 during thermal expansion and contraction.

Fig. 4 is a partial top view of the backlight module of the second embodiment before being bent. Fig. 5 is a schematic cross-sectional view of the backlight module of the second embodiment in a second direction. As shown in fig. 4, the second bending portion 37 of the quantum dot film 30 includes a folding line 371, and the folding line 371 extends along a direction parallel to the width direction of the light guide plate 20, that is, along the extending direction of the non-incident surface 25. As shown in fig. 5, after bending, a bump can be generated, thereby ensuring the length adjustment during expansion and contraction and avoiding light leakage.

Fig. 6 is a partial top view of the backlight module of the third embodiment before bending. Fig. 7 is a schematic cross-sectional view of a backlight module of a third embodiment in a second direction. As shown in fig. 6, the second bent portion 37 of the quantum dot film 30 includes a plurality of folding lines 371, and the folding lines 371 extend in parallel to the width direction of the light guide plate 20. As shown in fig. 7, after bending, a saw-toothed structure can be generated, thereby ensuring the length adjustment during expansion and contraction and achieving the effect of avoiding light leakage.

FIG. 8 is a top view of an embodiment of a backlight module in a second direction. FIG. 9 is a bottom view of an embodiment of a backlight module in a second direction. As shown in fig. 8 and 9, in some embodiments, the side surface 45 of the metal back plate 40 is provided with a key slot 451, and the side wall 61 of the backlight frame 60 further includes a hook 611. The hooks 611 are engaged with the slots 451, so that the side surface 45 of the metal back plate 40 is coplanar with the side wall 61, thereby achieving the effect of thinning the periphery of the display. Further, although not shown in the drawings, it is understood that the side wall 43 of the metal back plate 40 may be omitted in this embodiment, and the light source 10 may be directly mounted on the side wall 61, so as to achieve the effect of a very narrow frame. Here, the metal back plate 40 may have a step, and the key groove 451 and the hook 611 may be one or more, and may have different shapes and sizes. In the drawings, which are intended to be exemplary only and not limiting, various ways of creating coplanar connections are applicable.

In summary, in the backlight module 1, the extending portion 33 of the quantum dot film 30 ensures that the extending portion 33 overlaps with the projection of the light source 10 in the vertical direction when the quantum dot film expands with heat and contracts with cold, and the bending

portions

35 and 37 of the quantum dot film 30 are bent to the non-light-incident surfaces 23 and 25 and are not connected to the bottom metal back plate 40. Therefore, the blue light leakage of the light source 10 is avoided, the phenomenon that the edge of the active area of the display is blue light is prevented, and the color gamut and the color balance of the display are ensured.

Although the present invention has been described with reference to the preferred embodiments, it is not intended to limit the invention. The present invention is capable of other embodiments, and various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A backlight module, comprising:

a light source;

a metal back plate with a bearing surface;

a light guide plate, located on the carrying surface of the metal back plate, including a light incident surface and a plurality of non-light incident surfaces, wherein the light source corresponds to the light incident surface, and a gap is formed between the light incident surface and the light source; and

a quantum dot film disposed on the light guide plate, the quantum dot film including a body, an extension portion and a plurality of bending portions, the body being disposed on the light guide plate, the extension portion extending from the body toward the light source, the extension portion being partially overlapped with the light source on a first projection plane parallel to the body, the bending portions extending toward the non-light-incident surface respectively, the bending portions being overlapped with the non-light-incident surface respectively on a second projection plane perpendicular to the first projection plane; wherein the bending part is not contacted with the bearing surface of the metal back plate;

wherein the length of the extension is represented by the following equation:

equation one:

wherein A is the length of the extension, A₁Is the length of the gap, A₂Length of the light source, Ly width of the light guide plate, and delta_LGPThe thermal expansion coefficient, delta, of the light guide plate_QDThe thermal expansion coefficient of the quantum dot film and Δ T are temperature change values.

2. The backlight module of claim 1, wherein the bending portions respectively cover the non-light incident surfaces.

3. The backlight module of claim 2, wherein the bending portion comprises a first bending portion and two second bending portions, the first bending portion is located on the opposite side of the extending portion, the two second bending portions are respectively connected to the first bending portion and the extending portion, wherein the length of the first bending portion is represented by the following equation two, and the length of the second bending portion is represented by the following equation three:

equation two: a is₁≥Lz，

Equation three:

wherein a is₁Is the length, a, of the first bending part₂The length of the second bending part, Lx the length of the light guide plate, Ly the width of the light guide plate, Lz the thickness of the light guide plate, and delta_LGPThe thermal expansion coefficient, delta, of the light guide plate_QDThe thermal expansion coefficient of the quantum dot film and Δ T are temperature change values.

4. The backlight module according to claim 3, wherein each of the second bending portions comprises a folding line extending along a direction parallel to a width of the light guide plate.

5. The backlight module according to claim 3, wherein each of the second bending portions comprises a plurality of folding lines extending in a direction parallel to the width direction of the light guide plate.

6. The backlight module of claim 1, wherein the bending portions are respectively adhered to the non-light incident surfaces of the light guide plate.

7. The backlight module of claim 1, further comprising a reflector plate and an optical sheet, wherein the light guide plate is disposed on the reflector plate, and the optical sheet is disposed on the quantum dot film.

8. The backlight module of claim 7, further comprising a backlight frame, wherein the backlight frame comprises a sidewall and an extension wall, the metal back plate further comprises a sidewall extending from one end of the supporting surface in a direction parallel to a thickness of the light guide plate, the sidewall is connected to the sidewall of the metal back plate, the light source is disposed on the sidewall, the sidewall extends in a direction parallel to the thickness of the light guide plate, the extension wall is connected to the sidewall and extends in a direction perpendicular to the thickness of the light guide plate, and a portion of the light source, the reflector, the light guide plate, the quantum dot film and the optical sheet is disposed between the metal back plate and the extension wall.

9. The backlight module of claim 8, wherein the metal back plate comprises a slot, and the sidewall of the backlight frame comprises a hook, the hook engaging with the slot, such that the metal back plate and the sidewall have a common plane.